The Church of St. John the Baptist is a domed cruciform church, built of undressed stone. It is one of the best preserved churches in Nesebar. It is 12 meters long and 10 meters wide. The structure of the church consists of two cylindrical vaults which intersect in the center of the composition. The masonry is crushed stone and pebbles and the facades were probably smoothly plastered. It was built in the 11th century. The altar space consists of three semi-circular apses. Four massive pillars support the dome and form the cross. Inside the church the walls are smooth and unbroken. The exterior is simple without decorative niches and ceramic plaques, typical of the ornamental style. Bricks were used as a decorative element over the entrance, in the jagged cornices and around the windows.
Some frescoes in the church have been preserved dating from later periods. The faded portraits of the donor and his contemporaries on the southern wall and the fragments beneath the dome date from the 14th century and the others are from the 16th and 17th centuries.
Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.